Patients with cancer often exhibit a profound weight loss which is associated with muscle wasting and anorexia. This weight loss is sometimes out of proportion to lack of dietary intake and has led to the belief that this disease may be associated with metabolic alterations in the host. Whether weight loss associated with neoplastic disease differs from that seen in the starving individual is unknown. Sustained weight loss is always associated with a negative nitrogen balance. This occurs at the expense of nitrogen provided by muscle. This muscle nitrogen loss is a fundamental characteristic of protein catabolism and the accepted standard for measuring this has become the qualitative and quantitative analysis of intracellular muscle amino acids. Characteristic muscle amino acid patterns are found with weight loss associated with trauma sepsis, starvation, diabetes and uremia. This had led to attempts to design diets which will specifically correct these deficits. No information is available on the amino acid patterns in the muscle of cancer patients. The purpose of this study is to evaluate the nutritional status of the cancer patient with and without weight loss by analyzing the free intracellular amino acids in muscle tissue as well as plasma amino acids.